<!DOCTYPE html>
<html>
    <head>
        <link rel="stylesheet" type="text/css" href="css1.css" />
        <script>
            function aa(){
                alert()
            }
        </script>
    </head>
    <body>
         <h2 onclick =  "aa()">aaaaaaaaaaaaaaaaa</h2>
    </body>
</html>